RF receivers are used in a variety of modern electronics, such as smart phones, digital radios, modems, routers, printers, and Internet gateways. FIG. 1 is a functional block diagram of an RF receiver constructed according to the prior art. As a may be seen, a receiver 10 includes a transformer in a balanced/unbalanced (BALUN 12) configuration in which the first terminal of a first port receives a single-ended receive signal from an antenna 14, and a second port is connected to produce the in-going RF signal to a low noise amplifier (LNA 16) that, in turn, produces an amplified in-going RF signal to a mixer or down conversion block 18 (generally, a mixing stage). Down conversion block 18 produces a frequency down converted signal to a filtering/gain block 20 that filters the received signal and provides additional amplification to generate a filtered and amplified signal to an analog to digital converter (ADC) 22 that produces a digital representation of the filtered and amplified signal to a processor 24 for processing.
For example, receiver 10 can be part of a transceiver that is used to support the transmission and reception of communication signals according to one or more of a variety of communication standards for relatively short communication distances, including near-field communication (NFC) having a distance of about 10 centimeters, personal area networks operative from 10 to 100 meters using a private as well as standardized communication protocols such as “ZigBee”, “Bluetooth” and Bluetooth low energy (BTLE), and wireless local area networks protocols including the various versions of I.E.E.E. 802.11 communication protocols for “WiFi” communications having a greater maximum distance. While WiFi range varies based on structural conditions and interference, under ideal conditions, a WiFi range of over 300 meters are possible.
These various standards are designed for particular purposes and generally have different power and signaling requirements. However many electronic products now support communications according to multiple standards, and provide separate circuitry for each standard at an increased product cost. Additionally, utilizing multiple transceivers in one device leads to shorter battery life. Accordingly, one design challenge is to design and build a low cost, reliable receiver using a common antenna that accommodates different receive signal strengths.
The use of the same reference symbols in different drawings indicates similar or identical items. Unless otherwise noted, the word “coupled” and its associated verb forms include both direct connection and indirect electrical connection by means known in the art, and unless otherwise noted any description of direct connection implies alternate embodiments using suitable forms of indirect electrical connection as well.